Auditory feedback for machine operators is widely used in a number of applications in business equipment. For example, electronic keyboards are widely used in modern data processing and similar equipment. Keyboard switches in such keyboards may take the form of two membrane-type members which must make contact with each other to provide a signal indicating that the key position has been actuated. The signal thus generated is normally decoded to generate binary data signals representing the actuated key. Such keyboards are essentially noiseless in operation and thus do not, of themselves, provide the auditory feedback that was present in earlier types of keyboards, such as those employing mechanical keys, to indicate to the user that the key had been depressed a sufficient distance to enter the information desired. In order to provide such auditory feedback, audio generators have been incorporated into keyboards to provide an audible tone representing the click sound which occurs, for example, in a mechanical keyboard upon full key depression. Various means have been employed to change the volume of the audio generator in response to varying noise conditions in the environment in which the apparatus employing the keyboard is used. One such system is shown in U.S. Pat. No. 4,694,725, issued Sept. 22, 1987, inventors Daniel B. Seevers and John J. Rohulich, assigned to the assignee of the present application. Other uses for auditory feedback in business machines include operator alert for price changes, scanner scale operations, check validation and cash drawer opening.